1. Field of the Invention
The subject invention is directed to an improved method of forming a non-ionic (neutral) late transition metal chelate which is useful as a catalyst for the polymerization of olefins. The improved method provides novel chelates which exhibit high catalytic activity for olefin polymerization.
2. Background of the Invention
The polyolefin industry has relied on various catalyst and free radical initiator systems to polymerize ethylene and other non-polar 1-olefins. Such polymerization has been accomplished using organometallic Ziegler-Natta coordination type catalysts, chromium catalysts, certain early transition metal catalysts, as well as free-radical type initiators. It is well known that these catalysts are highly susceptible to a range of substances which poison or deactivate their catalytic activity. For example, it is known that even trace amounts of oxygen, carbon monoxide, water, or organic substances having oxygen donor groups cause deactivation of transition metal catalysts. When such substances are present one is usually restricted to free radical initiator systems.
Two recent publications, WO 98/42664 and WO 98/42665, disclose certain novel late transition metal salicylaldimine and pyrrolaldimine chelates that can act as single-site olefin polymerization catalysts which are not oxophilic. Thus, these chelates may be used to catalyze the polymerization of ethylene alone or with other 1-olefins or cycloolefins including those having oxygen atom-containing functional groups (e.g., ether, ester, carbonyl, carboxyl, or hydroxy groups). Further, these chelates provide good catalytic activity and are resistant to being poisoned even when used in the presence of moisture or organic compounds having oxygen atom containing groups.
The disclosed process for forming these catalyst chelates includes initially deprotonating the appropriate ligand using a lithium alkyl or an alkali metal hydride followed by chelation of the deprotonated (anionic) ligand with a late transition metal coordination compound. Both of these process steps use reagents which are difficult to handle. Further, the process produces a late transition metal chelate which contains an ancillary ligand, such a triphenylphosphine, associated with the transition metal atom. It is believed that such ligand must be dissociated from the chelate to provide catalytic polymerization activity. Normally, such ligands do not completely dissociate; thus, chelates having such ancillary ligands exhibit catalytic activity which is lower than expected. Certain adjunct agents are taught to assist in ancillary ligand dissociation.
Another recent PCT publication, WO 98/30609, discloses a number of late transition metal chelates as being useful as olefin polymerization catalysts. These chelates may also contain inert functional groups, such as electron withdrawing groups, as part the chelate structure. The resultant chelate comprises a ligand group which may be a neutral bidentate ligand or a mono-anionic bidentate ligand associated with the metal atom of the chelate. In many instances the chelate exists in dimer form. Synthesis of these chelates is taught to be accomplished by protonation of suitable nickel(0) or nickel(II) precursors by a neutral ligand, preferably in the presence of phosphine or allyl ligand sponges such as copper chloride, triphenyl borane or the like.
The foregoing methods of forming non-ionic, bidentate late transition metal chelates provide products which exhibit only low or moderate catalytic activity. It would be highly desirable to have a process which is capable of forming non-ionic late transition metal chelates which are free of slow-to-dissociate ancillary ligand. Further, it would also be highly desirable to have a process which provides non-ionic late transition metal chelates which are storage stable. Still further, it would be highly desirable to have a process which provides non-ionic late transition metal chelates which exhibit high catalytic activity and extended polymerization life. It would also be highly desirable to provide a process for the polymerization of olefins where the catalyst is a highly active late transition metal chelate, where the chelate can be formed in situ in the polymerization media, and where the chelate is not poisoned by the presence of oxygenated compounds.
The present invention is directed to a process of forming non-ionic late transition metal chelates which have high catalytic activity for olefin polymerization. The present process does not require a metal alkyl- or metal hydride-assisted deprotonation of the ligand and produces chelates which are free of an associated (tightly bound) ligand entity. Further, one embodiment of the present process produces storage stable chelates. The present invention also provides a method of polymerization of 1-olefins alone or with functionalized olefins or cyclic olefins wherein the highly active catalyst is formed in situ in the polymerization medium. The process of the present invention eliminates the need for forming a mono-anionic form of the bidentate ligand and association of the resultant chelate with a labile phosphine or allyl type ligand, as preferred by prior processes.
The present process provides a highly active olefin polymerization catalyst including a neutral late transition metal chelate and involves contacting a dialkyl transition metal(II) diamine complex with a bidentate chelating ligand which is free of electron withdrawing groups and has certain sterically bulky substituents. Preferably, the ligand and dialkyl transition metal(II) diamine complex reagent are contacted in the presence of an aprotic polar liquid to provide a storage stable solid catalyst product. Alternatively, the chelate can be formed in situ and used as a polymerization catalyst.
The present invention is directed to a method of forming certain neutral, bidentate late transition metal chelates which remain stable during storage prior to use and to the storage stable chelates. The present invention is further directed to the formation of the chelates in situ and directly used as a polymerization catalyst.
The following terms are defined herein below to aid in providing a clear teaching of the present invention:
(A) xe2x80x9cHydrocarbylxe2x80x9d group refers to a univalent organic group composed of hydrogen and carbon. If not otherwise stated, it is preferred that said hydrocarbyl group contain from 1 to 40 carbon atoms.
(B) xe2x80x9cHydrocarbylenexe2x80x9d group refers to a divalent organic group composed of hydrogen and carbon. If not otherwise stated, said hydrocarbylene group may include aliphatic, aromatic and mixed aliphatic/aromatic groups.
(C) xe2x80x9cHydrocarbyloxyxe2x80x9d or xe2x80x9coxyhydrocarbylxe2x80x9d group refers to a univalent organic group composed of hydrogen, oxygen and carbon wherein the oxygen may be in the form of one or more ether oxygen, ester oxygen, ketone, aldehyde or carboxylic acid group(s) or mixtures thereof.
(D) xe2x80x9cHydrocarbyloxyenexe2x80x9d or xe2x80x9coxyhydrocarbylenexe2x80x9d refer to a divalent organic group composed of hydrogen, oxygen and carbon atoms wherein the oxygen atom may be in the form of an ether oxygen, ester oxygen, ketone, aldehyde or carboxylic acid group(s) or mixtures thereof.
(E) xe2x80x9cFunctional groupxe2x80x9d refers to ester, alcohol, carboxylic acid, halogen, primary, secondary and tertiary amine, aldehyde, ketone, hydroxyl nitro, and sulfonyl groups.
(F) xe2x80x9cArylxe2x80x9d and xe2x80x9carylenexe2x80x9d refer, respectively, to a monovalent and divalent carbocyclic aromatic ring which may consist of one or a plurality of rings (fused or non-fused).
(G) xe2x80x9cSubstitutedxe2x80x9d refers to an aryl or arylene group having one or more groups which do not interfere with the synthesis of the compound or the polymerization process for which the compound is contemplated wherein said one or more groups may be a hydrocarbyl, hydrocarbylene, oxyhydrocarbyl, oxyhydrocarbylene, inert functional group or the like.
(H) xe2x80x9cPolymerization Unitxe2x80x9d refers to a unit of a polymer derived from a monomer used in the polymerization reaction. For example, the phrase xe2x80x9calpha-olefin polymerization unitsxe2x80x9d refers to a unit in, for example, an alpha-olefin/vinyl aromatic copolymer, the polymerization unit being that residue which is derived from the alpha-olefin monomer after it reacts to become a component of the polymer chain.
(I) xe2x80x9cPolyolefinxe2x80x9d refers to any polymerization olefin, which can be linear, branched, cyclic, aliphatic, aromatic, substituted, or unsubstituted. More specifically, including in the term polyolefin are homopolymers of olefins, copolymers of olefins, copolymers of an olefin and a non-olefinic comonomer copolymerization with the olefin, such as vinyl monomers, modified polymers thereof, and the like. Specific examples include polypropylene homopolymers polyethylene homopolymers, poly-butene, propylene/alpha-olefin copolymers, ethylene/alpha-olefin copolymers, butene/alpha-olefin copolymers, ethylene/vinyl acetate copolymers, ethylene/ethyl acrylate copolymers, ethylene/butyl acrylate copolymers, ethylene/methyl acrylate copolymers, ethylene/acrylic acid copolymers, ethylene/methacrylic acid copolymers, modified polyolefin resins, ionomer resins, polymethylpentene, etc. and the like.
The catalysts formed by the process of the present invention are late transition metal chelates wherein the metal is chelated with a bidentate ligand represented by the generic formulae: 
wherein
R represents a C4-C24 (preferably C4-C12) hydrocarbyl such as a C4-C12 alkyl group (e.g., butyl, pentyl, hexyl, heptyl and the like and all isomers thereof); a cycloalkyl such as cyclopentyl, cyclohexyl, adamantyl and the like; an aryl such as phenyl, biphenyl, naphthyl, anthracenyl, phenanthrenyl, m-terphenyl, terphenyl and the like; an aralkyl such as triphenylmethyl and the like; a substituted aryl having at least one position (preferably the ortho position(s)) of the aromatic group (preferably phenyl) substituted with a C1-C12 alkyl or a fused or unfused aryl group or an oxyhydrocarbylene group. It is especially preferred that R be a sterically bulky group such as an aryl or substituted aryl or aralkyl group as described above, particularly 2,6-diisopropylphenyl, anthracenyl, terphenyl, m-terphenyl, trityl, and the like;
each Rxe2x80x2 and Rxe2x80x3 independently is selected from hydrogen or an R group, as stated above, provided at least one of the Rxe2x80x2 and Rxe2x80x3 groups is a hydrogen, preferably Rxe2x80x2 is a hydrogen and Rxe2x80x3 is an R group;
G represents an oxygen or sulfur atom;
E represents an OH, SH, or NHR group;
J represents xe2x80x94Oxe2x80x94 or xe2x80x94Sxe2x80x94 as part of a ring structure;
Y represents an OR, SR, or NRR group where R is defined as above, preferably a sterically bulky hydrocarbyl group; and
∪ represents a hydrocarbylene group which may comprise arylene, arylalkylene, alkarylene, cycloalkylene and/or alkylene group or a mixture thereof and wherein said groups may have carbon-carbon single covalent bonds only or combined with non-aromatic or aromatic carbon-carbon ethylenic double bonds within the hydrocarbylene structure.
For the ligand to be suitable to form a storage stable catalyst according to the present process, it must be free of electron withdrawing groups such as nitro, halo (chloro, bromo, etc.) sulfonate, carboxylate, perfluoroalkyl, sulfonyl and the like. Unexpectedly, when the present catalyst chelate is formed by the process described herein using a bidentate ligand reagent which is free of electron withdrawing groups and has sterically bulky groups (e.g., aryl, substituted aryl, aralkyl or highly branched C4-C24 alkyl), one is able to form a storage stable catalyst material having enhanced catalytic activity. The catalysts of the present invention retain high catalytic activity of at least about 105 g polymer/mol cat/hr, with activities of from about 105 to about 107 g polymer/mol cat/hr and higher being readily observed.
Specific examples of ligands found useful in the present invention are given below. 
wherein
each R1 independently is a C4-C24 hydrocarbyl, a substituted C4-C24 hydrocarbyl which preferably is sterically bulky (e.g., an aryl, substituted aryl, aralkyl or a branched alkyl), or an R1 group with an R2 or R3 group on a vicinal carbon together form a hydrocarbylene ring;
each R2 independently is a hydrogen, C1-C24 hydrocarbyl, substituted C1-C24 hydrocarbyl, an inert (non-electron withdrawing) functional group, or any two R2 groups together or an R2 group with an R1 or R3 which are on vicinal carbon atoms can form a hydrocarbylene ring;
each R3 independently is a C1-C24 hydrocarbyl, substituted C1-C24 hydrocarbyl, an inert functional group, or an R3 group with an R1 or R2 which are on vicinal carbon atoms can form a hydrocarbylene ring;
each R4 independently is a hydrogen atom, hydrocarbyl, or substituted hydrocarbyl;
each R5 independently is a sterically bulky C6-C24 hydrocarbyl or a sterically bulky C6-C24 substituted hydrocarbyl, preferably an aryl, aralkyl or a C1-C12 hydrocarbyl substituted aryl; and
G, E, J and Y are the same as defined as above.
Examples of hydrocarbyl and substituted hydrocarbyl groups are C4-C24 alkyl such as butyl, pentyl, hexyl, octyl, decyl, dodecyl, and the like and all isomers thereof; alkenyl groups such as 3-butenyl and the like; aryl such as phenyl, biphenyl, naphthyl, anthracenyl, terphenyl (all isomers), phenanthrenyl, and the like; alkaryl such as toluyl and the like; aralkyl such as trityl(triphenylmethyl), 4-(ethenylphenyl)diphenylmethyl and the like; and said hydrocarbyl groups having one or more substitution groups selected from C1-C12 alkyl, C1-C12 alkenyl, or a hydrocarbyl terminated oxyhydrocarbylene group xe2x80x94(BO)nR wherein each B independently represents a C1-C4 (preferably C2-C3) alkylene group or an arylene group and R represents a C1-C11 (preferably C1-C3) hydrocarbyl group such as an alkyl, unsubstituted or substituted aryl and n is an integer of 1-4.
To form a storage stable catalyst of the present invention, R5 of the above ligands and of the resulting catalyst chelate must be sterically bulky groups selected from aryl, such as for example phenyl, biphenyl, naphthyl, anthracenyl, phenanthrenyl, terphenyl (all isomers) and the like; aralkyl such as toluyl and the like; alkaryl such as trityl, 4-(ethenylphenyl)diphenylmethyl and the like and substituted aryl groups wherein the substitution is selected from C1-C12 alkyl, C1-C12 alkenyl or a hydrocarbyl terminated oxyhydrocarbylene group xe2x80x94(BO)nR as defined above. Further, for the resultant catalyst chelate formed according to the present invention to be storage stable, R1 must be a sterically bulky group selected from a C4-C24 branched alkyl such as, for example, t-butyl, 1,1-dimethyl propyl, 1-methyl-1-ethyl propyl, 1,1-diethyl propyl and the like; or an R5 group. Preferably, R1 and R5 both are sterically bulky groups independently selected from aryl, aralkyl, alkaryl, and substituted aryl groups as described above with respect to R5.
The ligand is contacted with di(tertiary amine) late transition metal reagent represented by the formula 
wherein
Rxe2x80x2xe2x80x3 represents hydrogen (preferable) or a C1-C5 alkyl or substituted alkyl;
RIV and RV each independently represents a hydrocarbyl, such as a C1-C10 alkyl, preferably C1-C3 alkyl and most preferably a methyl group or each RIV together and each RV together represents a hydrocarbylene group which may be aromatic or non-aromatic;
RVI each independently represents hydrogen, aryl, SiOR3 or a tri(C1-C12 hydrocarbyl)methyl group, xe2x80x94CRRR, wherein each R is a substituent independently selected from a C1-C12 hydrocarbyl as defined above, with hydrogen being preferred;
M represents a Group VIII transition metal selected from Fe, Co, Ni, Ru, Rh, Pd, Os, Ir or Pt in the +2 oxidation state, preferably Ni or Pd and most preferably Ni; and
n represents an integer of from 0 to 3, and preferably n is an integer of from 1 to 3, when each RIV and each RV is a hydrocarbyl with the proviso that n preferably is 0 when both RIV and both RV are hydrocarbylene groups.
The above reagents can be readily formed. For example, the nickel(II) chelate of tetramethylethylenediamine is formed by first contacting tetramethylethylenediamine with nickel(II) acetylacetonate in an inert hydrocarbon solvent, such as pentane, heptane, or the like. The nickel acetylacetonate product then is alkylated in an inert aprotic solvent such as diethylether, tetrahydrofuran, or the like at about xe2x88x9230xc2x0 C. with dimethyl magnesium tetramethylethylenediamine to provide a mixture of the desired (insoluble) ditertiary amine late transition metal agent [e.g. dimethyl nickel(II) tetramethylethylenediamine] and a soluble magnesium by-product. The desired metallation agent can be separated from the by-product by decanting the solvent which contains the soluble by-product and several washes of the insoluble (tmeda) Ni(CH3)2 with fresh polar aprotic solvent at xe2x88x9230xc2x0 C. The specific liquid to use depends on the solubility parameters of the reagent and by-product and can be readily determined by routine screening.
Preferred agents include late transition metal agents formed with tetramethylethylenediamine, and preferred metals include Ni(II) or Pd(II), most preferably Ni(II).
The present process includes contacting the bidentate chelating ligand described above with a late transition metal agent described above. The ligand and late transition metal agent are contacted in an inert liquid, preferably a polar aprotic liquid such as a nitrile, ether, aromatic heterocyclic amine and the like, as fully described below. The ligand and metal agent may be contacted at any temperature which does not cause degradation of the reactants or the chelate product, such as from between about xe2x88x9220xc2x0 C. to about 70xc2x0 C. or higher, preferably from about 0xc2x0 C. to about 50xc2x0 C.
In one embodiment of the subject invention, one forms a catalytically active, storage stable chelate product. (The term xe2x80x9cstorage stablexe2x80x9d refers herein and in the appended claims to a chelate product which can be isolated, does not dimerize or otherwise degrade and can be stored for periods of up to at least about 3 months, more generally up to at least about 6 months, while retaining its catalytic activity prior to utilization.) The process of forming a storage stable catalyst requires the ligand to be free of electron withdrawing groups such as, for example, nitro, halo (chloro, bromo, and the like), sulfonate, sulfonyl ester, carboxylate, perfluoroalkyl, and the like. Further, the present process requires a ligand which has sterically bulky groups thereon especially at the R1 and R5 positions of the ligand and resultant chelate.
The chelating ligand and the late transition metal agent are contacted in the presence of an aprotic polar liquid xe2x80x9cSolxe2x80x9d to provide a metal chelate product which has enhanced catalytic polymerization activity and maintains such activity while being storage stable. Examples of useful polar liquids S include nitrites (preferred) as, for example, acetonitrile (most preferred), propionitrile, butyralnitrile, benzonitrile, and the like; an ether as, for example, tetrahydrofuran, glyme, diglyme and the like; or an aromatic heterocyclic amine as, for example, pyridine, lutidine and the like. The aprotic liquid should be present in the reaction zone in at least a slight molar excess quantity based on the molar quantity of transition metal (e.g., at least 1.01 moles per mole of transition metal, more preferably at least 1.1 moles per mole of transition metal). The aprotic liquid can be used as some or all of the solvent of the reaction mixture.
A common identifying feature of the desired catalyst compound is the methyl NMR signal associated with the metal CH3 bond of the present chelates at about xe2x88x920.8 ppm or lower (depending on the identity of xe2x80x9cSolxe2x80x9d).
The above process of contacting a bidentate ligand free of electron withdrawing groups with a late transition metal agent in the presence of an aprotic polar solvent, as described above, produces a chelate product represented by the following formulae: 
wherein
R, Rxe2x80x3, G, E, J, Y, and ∪ correspond to the precursor ligand moiety of I to V described above which is used to form said chelate and R and Rxe2x80x3 of the resultant chelate are thus each independently selected from a C4-C24 hydrocarbyl selected from cycloalkyl, aryl, substituted aryl wherein the substitution is selected from a C1-C4 alkyl, an unfused or fused aryl or is a hydrocarbyl terminated oxyhydrocarbylene group;
RVI each independently represents hydrogen, aryl, SiOR3 or a tri(C1-C12 hydrocarbyl)methyl group, xe2x80x94CRRR, wherein each R is a substituent independently selected from a C1-C12 hydrocarbyl as defined above, with hydrogen being preferred;
M represents a late transition metal ion, that is a metal atom of Group IV or VIII transition metals, preferably selected from Fe, Co, Ni, Ru, Rh, Pd, Os, Ir or Pt in the +2 oxidation state, preferably iron, cobalt, nickel or palladium and still more preferably nickel or palladium with nickel being the most preferred; and
Sol represents an aprotic solvent molecule (described above) in association with the chelate.
The chelates XVII, XVIII, XIX, XX and XXI are formed from the ligands I, II, III, IV or V, respectively.
Examples of such neutral bidentate late transition metal chelates are given below (and correspond to the ligand precursors VI to XV and their respective groups described above): 
As stated above, the chelate product of the present process can be isolated, stored and used as a catalyst for the polymerization of a 1-olefin such as ethylene, alone, or in conjunction with a functionalized olefin or cyclic olefin, such as those disclosed in WO 98/42664 and WO 98/42665, the teachings of which are incorporated herein in their entirety by reference.
It is believed although not meant to be a limitation of the present invention, as described herein or defined in the claims appended hereto, that the chelate obtained by the process of the present invention wherein the precursor bidentate ligand is free of electron withdrawing groups, the bidentate ligand contains sterically bulky groups, and the bidentate ligand and metal agent are contacted to form the chelate in the presence of an aprotic polar liquid provide a neutral chelate which is free of an ancillary ligand group, such as triphenylphosphine or allyl, associated with the transition metal of the chelate. Although such ancillary ligand can disassociate from the metal when in the presence of a pi-bond olefin, such dissociation is not complete or rapid. The lack of substantially complete and rapid dissociation of an ancillary ligand from prior known chelates provide a catalytic activity which is substantially inferior to that of the chelate products presently produced wherein an aprotic solvent molecule xe2x80x9cSxe2x80x9d which is highly disassociative is a part of the chelate product.
A second embodiment of the subject invention is directed to a process of forming the neutral chelate in-situ in a polymerization process medium. In this embodiment the precursor ligand I-V and the late transition metal agent XVI described above are introduced into the polymerization zone to initiate and catalyze the polymerization of an olefin or of the copolymerization of an olefin and a functionalized olefin or cyclic olefin.
The polymerization may be carried out at conventional temperatures (e.g., about xe2x88x92100xc2x0 C. to about +200xc2x0 C., preferably from xe2x88x9220xc2x0 C. to +100xc2x0 C., and most preferably between 0xc2x0 C. and 70xc2x0 C.). All ranges of temperatures being covered by this teaching. The pressure of the polymerization may be from atmospheric pressure to about 100 MPa or more, with all ranges of pressure being covered by this teaching. The polymerization is preferably carried out in a liquid which also acts as a liquid medium in which the ligand and the transition metal agent contact each other. The liquid may be (i) the monomer(s), per se or (ii) any organic compound (preferably hydrocarbon) which is liquid under the polymerization conditions and is inert toward the monomers, polymer, ligand, metal agent, and resultant chelate.
In this second embodiment, an aprotic polar liquid may be present. If present, the aprotic polar liquid preferably is an ether as, for example, diethylether, glyme, diglyme, tetrahydrofuran and the like; a nitrile as, for example, acetonitrile, propionitrile, butyralnitrile, benzonitrile or the like; an aldehyde or ketone, such as acetone, propanone, cyclohexanone, acetaldehyde, benzaldehyde and the like; an alcohol such as methanol, ethanol, propanol, butanol and the like; organic esters such as ethyl acetate, propylacetate, ethyl laurate and the like; nitroalkanes and nitroaromatics such as nitropropane, nitrobenzene and the like; as well as mixtures thereof.
Further, when forming the catalyst chelate in situ in the polymerization zone, the ligand and, therefore, the resultant chelate catalyst formed in situ may have an electron withdrawing group as part of the molecule. When such groups are present, they may be a substituent moiety of a hydrocarbyl of R1, R2, R3, R4 or R5 and preferably of the hydrocarbyl of R1 and/or R5 sterically bulky groups selected from C4-C24 hydrocarbyl such as an aryl, substituted aryl or a highly branched alkyl group. When such groups are present as part of ligand VI, the position para with respect to the G moiety preferably is an electron withdrawing group.
One of the advantages of this second embodiment is that the present chelate catalyst can be formed in-situ in the polymerization media from easy to handle reagents. Further, the polymerization media need not contain a xe2x80x9cspongexe2x80x9d for phosphine or allyl-type ancillary ligand, as is commonly used with prior taught bidentate chelate catalysts. Finally, the present process provides a catalyst which exhibits enhanced activity over that provided for by prior modes of formation.
This invention also concerns processes for making polymers and copolymers that includes contacting the subject catalyst composition with one or more selected olefins or cycloolefins, alone or optionally with a functional 1-olefin such as a carboxylic acid of the formula CH2xe2x95x90CH(CH2)mCOOH, a carboxylic acid ester of the formula CH2xe2x95x90CH(CH2)mCO2R4 or CH2xe2x95x90CHOCOR14, an alkyl vinyl ether of the formula CH2xe2x95x90CH(CH2)mOR14, vinyl ketones of the formula CH2xe2x95x90CH(CH2)mC(O)R14, a vinyl alcohol of the formula CH2xe2x95x90CH(CH2)mOH, or a vinyl amine of the formula CH2xe2x95x90CH(CH2)mNR142, wherein m is an integer of 0 to 10 and R14 is a C1-C10 hydrocarbyl group, aryl or substituted aryl group (preferably methyl); a functional cycloolefin, such as an exo-functionalized norbornene wherein the functional group is an ester, alcohol, carboxylic acid, halogen atom, tertiary amine group or the like; unsaturated dicarboxylic acid anhydride or carbon monoxide or the like; and other selected monomers such as vinyl halides. The xe2x80x9cpolymerization processxe2x80x9d described herein (and the polymers made therefrom) is defined as a process which produces a polymer with a weight average molecular weight (Mw) of at least about 10,000.
Catalytic polymerization according to the present invention can be carried out by contacting one or more selected olefins or cycloolefins alone or optionally with a functional olefin or cycloolefin monomer, as described above with a neutral catalyst chelate which has been previously formed according to the present invention or which is formed in-situ from one or more of the bidentate ligands described above and a transition metal reagent. When the polymerization process is carried out according to the second embodiment described herein, the ligand and reagent should be used in about 1:0.75 to 1:1.5 molar ratio. In a preferred embodiment of the present invention, the bidentate ligand is combined with a transition metal reagent in about a 1:1 to 1:1.05 molar ratio in the presence of olefin and/or cycloolefin alone or optionally with a functional olefin monomer. The catalyst thus formed in situ may further contain a Lewis base additive, such as ethers, esters, ketones, aldehydes, and the like.
With respect to all catalysts and precursor bidentate ligands described herein, R1 and R5 each is preferably independently a sterically bulky hydrocarbyl. In one form, R1 and/or R5 preferably are independently selected from a hydrocarbyl-terminated oxyhydrocarbylene containing group, as described above. Also, R1 and R2 can be taken together to provide a hydrocarbylene which forms a carbocyclic ring. It is preferred that R2, R3 and R4 are hydrogen or methyl unless R2 is, when taken together with R1 or R3, a C4-C10 carbocyclic group which may or may not be aromatic. Either or both R1 and R5 preferably are phenyl, biphenyl, terphenyl (all isomers included), naphthyl, anthracenyl, phenanthracenyl, trityl, vinyltrityl, 2,6-diisopropylphenyl, 2,6-dimethylphenyl, 2,6-diethylphenyl, 4-methylphenyl, 2-isopropyl-6-methylphenyl, 2,4,6-trimethylphenyl, 2-t-butylphenyl, 2-t-butyl-4-methylphenyl, or 2,6-diisopropyl-4-methylphenyl.
The structure of the bidentate ligand and the resultant chelate with which it is associated may influence the polymer microstructure, polymer yield, and polymer molecular weight. For example, as described above, R1 and R5 each preferably is a bulky aryl or substituted aryl group. Complexes with R1 of this type generally produce higher molecular weight, higher polymer yield and more linear polymer product for any given set of conditions. The neutral chelate resulting from the present process is contacted, usually in the liquid phase, with an olefin such as ethylene alone or with another 1-olefin and/or 4-vinylcyclohexane, 4-vinylcyclohexene, cyclopentene, cyclobutene, substituted norbornene, or norbornene. The liquid phase may include a compound added just as a solvent and/or may include the monomer(s) itself and/or may comprise a Lewis base (especially an ether or nitrile compound) in the liquid phase at reaction conditions. The temperature at which the polymerization is carried out is from about xe2x88x92100xc2x0 C. to about +200xc2x0 C., preferably about xe2x88x9220xc2x0 C. to about +100xc2x0 C. and most preferably between about 0xc2x0 C. and 70xc2x0 C., with all substituent ranges of temperatures being covered by this teaching. The pressure at which the polymerization is carried out is not critical, with atmospheric pressure to about 100 MPa or more being a suitable range. The pressure may affect the yield, molecular weight and linearity of the polyolefin produced, with increased pressure and lower temperature providing more linear and higher molecular weight polymer product.
Preferred 1-olefins and cyclic olefins in the polymerization are one or more of ethylene, propylene, 1-butene, 1-hexene, 1-octene, 1-pentene, 1-tetradecene, norbornene, and cyclopentene, with ethylene, propylene, cyclopentene and norbornerie being more preferred. Ethylene (alone as a monomer) is especially preferred.
The polymerization may be conducted in the presence of various liquids. The solvent in which the polymerization may be conducted can be selected from (i) the monomer(s), per se or (ii) any organic compound which is liquid under the reaction conditions and is substantially inert to the reactants and product, or (iii) a Lewis base additive (except water which, when used, should be present in limited amounts) which is liquid under the reaction conditions, or mixtures thereof. Particularly preferred additives are aprotic organic liquids or organic ethers, organic nitriles or mixtures thereof. The catalyst systems, monomer(s), and polymer may be soluble or insoluble in these liquids, but obviously these liquids preferably do not inhibit the desired polymerization. Suitable liquids include alkanes, cycloalkanes, halogenated hydrocarbons, ethers, and aromatic and halogenated aromatic hydrocarbons. Specific useful solvents include hexane, heptane, toluene, xylene, and benzene, methylene chloride, ethyl ether, chlorobenzene, dimethoxyethane, tetrahydrofuran and crown ethers.
The catalyst formed according to the present invention can facilitate the polymerization of one or more 1-olefin(s) with functional olefins such as those described above. Carbon monoxide unexpectedly has been found to be useful as a comonomer to form alternating copolymers with the various 1-olefins using the catalytic process of the present invention. The polymerization is carried out with both CO and the olefin simultaneously present in the process mixture, and in the presence of the present catalyst. Such polymerization is carried out under conditions described above. The presently derived catalyst has been unexpectedly found to be more tolerant to carbon monoxide and thereby achieves higher conversion of carbon monoxide into the resultant copolymer than prior taught catalyst compositions.
The neutral catalysts of the present invention, when previously formed according to the first embodiment described above, may be supported on a porous solid material (as opposed to just being added as a suspended solid or in solution), for instance on silica gel, zeolite, alumina, crosslinked organic polymers such as styrene-divinylbenzene copolymer, and the like. By supported is meant that the catalyst may simply be carried physically on the surface of the porous solid support, may be adsorbed, or may be carried by the support by other means.
The present catalyst has been found to be particularly suitable for use on a support and as a catalyst for gas phase polymerization processes. This is very useful as the present catalyst does not require the presence of an activator (co-catalyst) or adjunct agent.
In many of the polymerizations, certain general trends may occur, although for all of these trends there are exceptions. Pressure of the monomers (especially gaseous monomers such as ethylene) has an effect on the polymerizations in many instances. Higher pressure often reduces branching and extends polymer chain length, especially in ethylene containing polymers. Temperature also affects these polymerizations. Higher temperature usually increases branching and reduces molecular weight of the polymer product.
The resultant polymers formed according to the present invention, especially those of ethylene homo or copolymers may have varying degrees of branching in the polymer. Branching may be determined by NMR spectroscopy, and this analysis can determine the total number of branches, the branching distribution and, to some extent, the length of the branches. The amount of branching is usually expressed as the number of branches per 1000 of the total carbon atoms present in the polymer, with one exception. Methylene groups that are in an ester grouping, i.e., xe2x80x94CO2R, or a ketone group, i.e., xe2x80x94C(O)R, are not counted as part of the 1000 carbons. For example, ethylene homopolymers have a branch content of about 0 to about 150 branches per 1000 carbon atoms, preferably about 5 to about 100 and most preferably about 2 to about 70 branches per 1000 carbon atoms. These branches do not include polymer end groups. Alternatively, branch content can be estimated from correlation of total branches as determined by NMR with polymer melting point as determined by differential scanning calorimetry.
The polymers formed by the present invention may be mixed with various additives normally added to elastomers and thermoplastics [see EPSE (below), vol. 14, p. 327-410] which teaching is incorporated herein by reference. For instance reinforcing, non-reinforcing and conductive fillers, such as carbon black, glass fiber, minerals such as silica, clay, mica and talc, glass spheres, barium sulfate, zinc oxide, carbon fiber, and aramid fiber or fibrids, may be used. Antioxidants, antiozonants, pigments, dyes, slip agents, antifog agents, antiblock agents, delusterants, or compounds to promote crosslinking may be added. Plasticizers such as various hydrocarbon oils may also be used.
The polymers formed by the present invention may be used for one or more of the applications listed below. In some cases a reference is given which discusses such uses for polymers in general. All of these references are hereby included by reference. For the references, xe2x80x9cUxe2x80x9d refers to W. Gerhartz, et al., Ed., Ullmann""s Encyclopedia of Industrial Chemistry, 5th Ed. VCH refers to Verlagsgesellschaft mBH, Weinheim, for which the volume and page number are given, xe2x80x9cECT3xe2x80x9d refers to the H. F. Mark et al., Ed., Kirk-Othmer Encyclopedia of Chemical Technology, 4th Ed., John Wiley and Sons, New York, xe2x80x9cECT4xe2x80x9d refers to the J. I. Kroschwitz, et al., Ed., Kirk-Othmer Encyclopedia of Chemical Technology, 4th Ed., John Wiley and Sons, New York, for which the volume and page number are given. xe2x80x9cEPSTxe2x80x9d refers to H. F. Mark et al., Ed., Encyclopedia of Polymer Science and Technology, 1st Ed., John Wiley and Sons, New York, for which the volume and page number are given, xe2x80x9cEPSExe2x80x9d refers to H. F. Mark et al., Ed., Encyclopedia of Polymer Science and Engineering, 2nd Ed., John Wiley and Sons, New York, for which volume and page numbers are given, and xe2x80x9cPMxe2x80x9d refers to J. A. Brydson, Ed., Plastics Materials, 5th Ed., Butterworth-Heineman, Oxford, UK, 1989, and the page is given. In these uses, a polyethylene, polypropylene and a copolymer of ethylene and propylene are preferred.
1. The polyolefins herein are especially useful in blown film applications because of their particular rheological properties (EPSE, vol. 7, p. 88-106). These polymers preferably have some crystallinity.
2. The polymers are useful for blown or cast films or as sheet (see EPSE, vol. 7 p. 88-106; ECT4, vol. 11, p. 843-856; PM, p. 252 and p. 432ff). The films may be single layer or multilayer, the multilayer films may include other polymers, adhesives, etc. For packaging the films may be stretch-wrap, shrink-wrap or cling wrap and may also be heat sealable. The films are useful for many applications such as packaging foods or liquids, geomembranes and pond liners. These polymers also preferably have some crystallinity.
3. Extruded films or coextruded films may be formed from these polymers, and these films may be treated, for example by uniaxial or biaxial orientation after crosslinking by actinic radiation, especially electron beam irradiation. Such extruded films are useful for packaging of various sorts. The extruded films may also be laminated to other films using procedures known to those skilled in the art. The laminated films are also useful for packaging of various sorts.
4. The polymers, particularly if elastomeric, may be used as tougheners for other polyolefins such as polypropylene and polyethylene.
5. Tackifiers for low strength adhesives (U, vol. A1, p. 235-236) are a use for these polymers. Elastomers and/or relatively low molecular weight polymers are preferred.
6. An oil additive for smoke suppression in single-stroke gasoline engines is another use. Elastomeric polymers are preferred.
7. The polymers are useful as base resins for hot melt adhesives (U, vol. A1, p. 233-234), pressure sensitive adhesives (U, vol. A1, p. 235-236) or solvent applied adhesives. Thermoplastics are preferred for hot melt adhesives.
8. Base polymer for caulking of various kinds is another use. An elastomer is preferred. Lower molecular weight polymers are often used.
9. Wire insulation and jacketing may be made from any of the polyolefins (see EPSE, vol. 17, p. 828-842). In the case of elastomers it may be preferable to crosslink the polymer after the insulation or jacketing is formed, for example by a free radical process.